Electric time clock correction



Sept. 8, 1931. G. F. HARTER 7 1,822,145

ELECTRIC TIME CLOCK CORRECTION Original Filed Oct'. 15, 1927 PatentedSept. 8, 1931 UNITED STATES PATENT OFFICE GEORGE F. HARTER, OFSPRINGFIELD, MASSACHUSETTS, ASSIGNOR TO THE STANDARD ELECTRIC TIMECOMPANY, OF SPRINGFIELDrIASSACHUSETTS, A CORPORATION OF I CONNECTICUTELECTRIC 'rmr: CLOCK CORRECTION Original application filed October 15,1927, Serial No. 226,317. Divided and this application filed July 27,1928, Serial No. 295,782. Renewed October 6, 1980.

My invention relates to electric clocks and electric clock systems ofthe type wherein a master clock which is very accurate controls, bymeans of electric circuits, the operation of several less expensivesecondary clocks, and more particularly to those secondary clocks whichoperate wholly by means of electric impulses received from the masterclock.

Periodically, usually each minute, such clocks are advanced by anelectric impulse from the master clock. In the course of 24 hours thereare 1440 such impulses and if for any reason such impulses fail evenonce, the secondary clock or clocks w1ll show 1I1COI- rect time. If allsecondary clocks become slow the same amount they may be advanced byhandby a set key usually proided at the master clock for that purpose. Butsometimes, because of a weak battery for example, some secondary clocksfail to receive suflicient current to operate them more often thanothers. It then becomes necessary to make the rounds of all thesecondary clocks and set them individually or at least make sure theyneed no setting.

One purpose of my invention is to provide for the automatic setting ofthe secondary clocks at less frequent intervals than the operatingimpulses are sent; and to automatically bring all secondary clocks tothe'same time regardless of whether they are all 1n error the sameamount. My invention also makes it possible to set groupsof secondaryclocks from the master clock instead of individually because myinvention not merely advances the secondary clocks, but actually setsthem. I prefer to set these secondary clocks once each hour, although itis obvious that other intervals may be selected and I do not wish toconfine myself to an hourly setting.

Heretofore a source of electricity, either primary or storage batteries,has been selected which would be as dependable as possible. Because ofthe danger of interruption of central station power due to blown fusesor other causes, such power has very rarely been used. But because ofthe frequency and certainty with which the secondary clocks are set bymeans of my invention, it is no longer necessary to provide at greatexpense against all minor interruptions of the source of current supply.I do not mean that I have dispensed with batteries in all cases but theobjection to any source of power because it is subject to minorinterruption is no 1onger 3 as serious as formerly. V

For the purpose of illustratin the genus of the invention one concreteem odiment is shown in the accompanying diagram, this embodiment beingada ted for use in any suitable system such, or example, as disclosed incopending application Serial No. 226,317, filed October 15, 1927, ofwhich this is a division.

At 34 is shown generally a secondary clock mechanism embodying thepresent invention. Those parts which are old but necessary to anunderstanding of my invention will be described first. The shaft 35 isrotated once each hour. Carried by the shaft 35 is a ratchet wheel 36which is impelled forward once each minute by the pawl 37 carried by thelever 38. Lever 38 is pivoted at 39 and carries an armature 40 which isattracted by magnet 41. A second ratchet wheel 42 is also carried byshaft 35 and in cooperation with pin 43 prevents shaft 35 from jarringforward during the time between impulses. Pawl 44 prevents backwardrotation of shaft 35 and spring 54 retracts lever 38 after magnet 41 hasceased to attract armature 40.

In addition to the usual mechanism described in the foregoing paragraphI employ a corrective magnet 45 which. operates on the armature 46 whichis carried by stop lever 55. Lever is pivoted at 47 and carries a stop48, a second stop 49 slightly advanced from the first stop, and a pin50. Non-rotatably attached to shaft 35 is a cam 51 carrying a pin 52 andhaving a cam face 53 adapted to be actuated by pin 50.

As shown in the figure. the stop 48 normally stands in the path of pin52 on cam 51 and if the clock hands actuated by 35 get ahead of timestop 48 stops further advance of the clock beyond the 59th minuteposition until corrective magnet 45 is energized on the hour to move thestop 48 out of the path of pin 52. If the clock has lost time during thehour, pin 50 engages cam 53 to advance is slightly ahea' of stop 48 thereturn of stop 48 to normal position can not block pin 52. The pin 52may be provided with a beveled top as shown in the figure so that itwill come under stop 48 if it doesnot entirely clear the stop as lever55 returns to normal position.

Thus impulses transmitted to magnet 41 through conductors 58 and 59 (bysuitable mechanism such as disclosed in'said application for example) atsuitable intervals, such as once per minute, cause the clock hands toadvance intermittently; and at the end of each hour (or at otherpredetermined intervals) an impulse is transmitted through conductors 59and 61 (by suitable mechanism such as disclosed in said application forexample) to corrective magnet 45 at the same time as magnet 41 isenergized, thereby causing the secondary clock 34, as well as othersimilar clocks connected in parallel therewith through conductors 58',59 and 61', to start the new hour on time irrespective of any inaccuracydeveloped during the preceding hour as above described.

It will thus be seen that I have provided a simple and accurate meansfor rectifying errors of the secondaryclock at definite intervals oftime and to bring all secondary clocks into exact agreement whetherfast, slow or correct and whether they all have the same error ordifferent errors.

From the foregoing it will be evident that the resent inventioncomprises a secondary clock of the type normally operable by recurrentimpulses from a master clock characterized in that the resetting ,meansis responsive to current of either polarity, thereby eliminating theunreliability of polarized magnets. Moreover such non-polarized means isof course ordinarily responsive to alternating current. Anotherimportant characteristic consists in that an abutment (52) moves in anorbital path (a true circle in the illustration) and stop means (48, 49etc.) has a part (48) which is transferred from one side to the other ofthe abutment in response to a single impulse of current at the end ofeach cycle (once per hour in the illustration) whereby the stop isautomatically repositioned for engagement with the abutment at the andof the next succeeding cycle.

' I claim:

1. A secondary clock of the impulse type comprising a clock train,impulse means, and

corrective means ha I a. stop normally preventing the advance said clocktram beyond a predetermined point, said corrective means being' operableto simultaneously remove the stop and advanoe'the clock train.

2. In a secondary clock of the impulse type having a clock train,corrective means com rising a cam and a pin carried by the clock train,and a stop lever having a stop lyingw normall' in the path of said pin,a second stop slightly advanced beyond the first stop and normally lyingoutside the path of said pin, and an arm on said lever cooperating withsaid cam to advance the clock train when the lever is operated, saidoperation simultaneously withdrawing the first stop from and introducingthe second stop into the path of the pin.

3. In a secondary clock of the im ulse type having a clock trainincluding a s aft, a ratchet wheel fixed thereto and an im ulse magnetfor advancing the ratchet whee and shaft, the combination of a cam andpin carried by said shaft, a stop lever, a magnet for moving said stoplever, said stop lever being in operative position prior to apredetermined time whereby said pin and shaft are not allowed to advancebeyond a predetermined position and said stop lever being moved at saidpredetermined time to advance said cam and shaft.

4. A secondary clock normally operable by recurrent impulses from amaster clock comprising a stop for blocking the advance of the clocktrain immediately preceding predetermined time intervals if the clock befast, and non-polarized electromagnetic means for concomitantly.rendering said stop inoperative and advancing the clock beyond thestopped position at said interva s.

5. A secondary clock normally operable by recurrent impulses from amaster clock comprising a stop for blocking the advance of the clocktrain immediately preceding predeter- 6. A secondary clock normallyoperable by recurrent impulses from a master clock, an abutment movingin an orbital path with the clock train, a stop for blocking the trainwhen the abutment reaches a predetermined point in said path, said stopincluding a part disposed in front of said abutment when the latterreaches said point, and means operative in response to a single impulseof vcurrent to transfer said part from the front to the rear of saidabutment, thereby permitting continued advance of the clock train.

7. A secondary clock normally operable by recurrent impulses from amaster clock, an

abutment moving in an orbital path with the clock train, a stop forblockingthe train when the abutment reaches a predetermined 7 point insaid path, said stop including a part disposed in the path of saidabutment when the latter reaches said point, and means operative inresponse to a single impulse of current to transfer said part from oneside to the other of said abutment, thereby permitting continued advanceof the clock train.

8. A secondary clock normally operable by periodic impulses from amaster clock, an abutment moving in an orbital path through recurrentcycles, a stop arranged to block the clock train by engagement with saidabutment when the abutment reaches a predetermined point in said path,and means operative in response to a single impulse to release theclocktrain and reposition the parts again to block the train after theabutment has completled another cycle around said orbital pat 9. Asecondary clock system of the impulse type comprising a clock train,means including an electromagnetic Winding for moving the clock train inrecurrent cycles, means for terminating further advance of the clocktrain at a predetermined point in each cycle if the clock is fast, meansincluding a second electromagnetic winding in. the secondary clockcontrolling further advance of the clock train, and circuits for saidwindings respectively whereby one may be rendered operativeindependently of the other.

10. A secondary clock system of the impulse type comprising a masterclock for transmitting to the secondary clock regular driving impulsesand periodic starting impulses, a plurality. of conductors forseparately transmitting said impulses to the secondary clock,clock-advancing means in each secondary clock normally responsive tosaid driving impulses, said means including an electromagnetic windingconnected to one of said conductors, means in each secondary clock forlimiting the advance of the clock train beyond a pre determined point ineach predetermined cycle of time if the clock is fast, and means in eachsecondary clock controlling further advance' of the clock after it hasbeen corrected, said last means including an electromomentarily movedout of said position, and

meansfor periodically. causing said obstruction to move out of saidposition and immediately back to said position.

12. A secondary clock of the impulse type in which the clock train isadvanced intermittently by equal steps, means in the clock for limitingthe advance of its clock train beyond. a predetermined point in eachredetermined cycle of time if the clock is ast, said means :including anobstruction for physically blocking further advance, said obstructionmoving out of blocking position and back again in response to a singleimpulse thereby permitting further advance of the clock train, and meansfor appl ing a momentary impulse to said obstructlon at regularpredetermined intervals.

igned by me at Springfield, Massachusetts, this 24th day of July, 1928.

GEORGE F. HARTER.

